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This paper reports on the corrosion performance of composite zinc layers (~ 8µm) on a steel substrate, considering the influence of nano-aggregates and Cr(III) conversion layers, compared to control (only Zn layers) conditions. The main factors, influencing the corrosion performance of Zn in this study are: a) the effect of two concentrations of polymeric nano-aggregates (0.1g/l and 0.3g/l PEO 113 -b-PS 218 core-shell micelles in the starting electrolyte); b) the effect of Cr(III) conversion layers on both pure Zn and composite Zn layers. For most of the hereby investigated time intervals i.e. treatment in aerated 5% NaCl from 2h until 120h, the composite coatings present higher corrosion resistance, especially within longer treatment. Corrosion current densities are similar to Zn, however, anodic currents are significantly lower. After treatment in NaCl, the composite Zn coatings present a more homogenous product layer, formed as a result of the presence of the nano-aggregates. The additional Cr(III) treatment does not significantly improve the corrosion resistance of the composite coatings for the hereby investigated time intervals.

This study reports on a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers in 5% NaCl solution. The metallic matrix of the ZnC layers incorporates nano-sized, stabilized polymeric aggregates, formed from the amphiphilic tri-block co-polymer: poly(2-hydroxyethyl methacrylate) -poly (propylene oxide -poly (2-hydroxyethyl methacrylate) (PHEMA 15 PPO 34 PHEMA 15 ). The main objective was to evaluate the electrochemical properties and surface characteristics of both coatings, thus further to investigate if the nano-composite layers will have better corrosion resistance, compared to pure galvanic zinc. The electrochemical behavior, investigated by Impedance spectroscopy (EIS) and Scanning vibrating electrode technique (SVET), supported by surface analysis, using Atomic-force microscopy (AFM) and Scanning electron microscopy (SEM), reveals higher corrosion resistance and consequently better performance of the nano-composite layers, compared to pure galvanic zinc. The mechanism of incorporation of the polymeric nano-aggregates in the coating and their influence on the barrier properties of the composite layers are also briefly discussed.